Photographic dry copying process with acylacetonitrile

ABSTRACT

PHOTOGRAPHIC IMAGES ARE PRODUCED BY (1) IMAGEWISE EXPOSING A LIGHT-SENSITIVE LAYER CONTAINING AT LEAST ONE SENSITIZING DYE FROM THE CLASS OF THE NEUTROSTYRYL DYES, THE MEROOCYANINES OR A CYANINE DYE CONTAINING A HALOGEN SUBSTITUTED BENZENE RING OR A HETEROCYCLIC RING DERIVED FROM SELENAZOL, A COMPOUND OF HE GUANIDINE OR BIGUANIDE SERIES AND AN IMAGE-PRODUCING REDUCING ACYLACETONITRILE DERIVATIVE WHICH IS TRANSFERABLE AT TEMPERATURES BETWEEN 80 AND 200*C, WHEREBY AT THE EXPOSED AREAS THE IMAGE-PRODUCING REDUCING COMPOUND IS CONVERTED TO A NON-TRANSFERABLE COMPOUND, (2) BRINGING THE EXPOSED LAYER INTO CONTACT WITH AN IMAGE-RECEIVING LAYER WITH CONTAINS COMPOUNDS CAPABLE OF REACTING WITH THE IMAGE-PRODUCING COMPOUND TRANSFERRED FROM THE UNEPOSED AREAS OF THE LIGHT-SENSITIVE LAYER TO FORM COLORED PRODUCTS AND (3) HEATING THE LAYERS WHILE IN CONTACT WITH EACH OTHER TO A TEMPERATURE OF BETWEEN 80 AND 200*C. TO PRODUCE A VISIBLE IMAGE.

United States Patent US. CI. 9629 D Claims ABSTRACT OF THE DISCLOSURE Photographic images are produced by (1) imagewise exposing a light-sensitive layer containing at least one sensitizing dye from the class of the neutrostyryl dyes, the merocyanines or a cyanine dye containing a halogen substituted benzene ring or a heterocyclic ring derived from selenazol, a compound of the guanidine or biguanide series and an image-producing reducing acylacetonitrile deriva- -tive which is transferable at temperatures between 80 and 200 C., whereby, at the exposed areas the image-producing reducing compound is converted to a non-transferable compound, (2) bringing the exposed layer into contact with an image-receiving layer which contains compounds capable of reacting with the image-producing compound transferred from the unexposed areas of the light-sensitive layer to form colored products and (3) heating the layers while in contact with each other to a temperature of between 80 and 200 C. to produce a visible image.

The invention is concerned with a photographic dry copying process and a light-sensitive material for carrying out this process.

Photographic processes that produce copies by dry methods are known per se. These processes make use of materials containing lightor heat-sensitive layers which are imagewise exposed or heated thus causing a photochromic reaction which bring about the formation of the image.

The known light-sensitive materials of the type mentioned above, from which negative images can be produced, have, however, several disadvantages. For example, their light sensitivity-especially in the visible region of the spectrumis unsatisfactory so that too lengthy copying times are required and the reproduction of colored originals present difliculties. Moreover, the finished images still remain sensitive to light and their stabilization with respect to daylight can, in general, be achieved only by a quite complicated after-treatment.

Processes for the production of copies are also known in which a light-sensitive coating, which contains a lightsensitive compound and an image-producing compound transferable to an image-receiving layer, is exposed to the image so that at the exposed areas the image-producing compound is converted to a non-transferable compound; the exposed layer is brought into contact with an imagereceiving layer which contains compounds that react with the image-producing compound to form a dye and the layer while in contact with each other are heated to a temperature at which the image-producing compound is transferred from the exposed areas of the light-sensitive layer to the image-receiving layer.

To these processes belong, for example, the so-called heat-development processes in which light-sensitive materials having a silver halide emulsion layer which contains a photographic developer are employed. After exposure, they are developed by heating in contact with an imagereceiving layer which contains substances capable of yielding a dye by reaction with the developer. When heated,

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the developer is transferred from the unexposed areas of the light-sensitive coating to the image-receiving layer to produce a dye image.

A disadvantage of these known heat development or developer-sublimation processes is the unsatisfactory storage of the silver halide emulsion layer containing the developer caused by the presence of substances that increase the residual moisture of the layers, such as salts which form hydrates or glycols, and by the increased sensitivity to oxidation of most developers in these slightly hardened or unhardened emulsion layers with high residual moisture.

The process described in USP No. 3,094,417 is also of this type. In this process light-sensitive emulsions are employed containing a transferable compound and a dye. On exposure the transferable compound, e.g. 4-methoxyl-naphthol is converted to a nontransferable product. By subsequent heating, this compound can be transferred from the unexposed areas to an image-receiving layer where it reacts with a silver salt, e.g. silver behenate to give a positive silver image.

A similar process has been described in 01.8 2,010,837 in which acetoacetonitrile derivatives which can be inactivated by light and which are capable of reacting with a silver salt are employed.

All these processes have the disadvantage that the sensitivity of the emulsion layers is often low or the stability of the material is limited or that the production of copies having a high gamma and high contrast presents difliculties.

It is among the objects of the present invention to provide photographic dry copying processes and lightsensitive materials suitable for such processes which are very sensitive to light and stable and which contain dyes which render the material sensitive to every required region of the spectrum and which allow the production of both multicolored and black images.

We now have found a process for the production of photographic images comprising the steps of (1) imagewise exposing a light-sensitive layer containing at least one sensitizer of the class of neutrostyryl dyes, merocyanines or a cyanine dye containing a halogen substituted benzene ring or a heterocyclic ring derived from selenazol, a compound of the guanidine or biguanide series and an image-producing reducing agent of the acylacetonitrile series, being transferable at temperatures in the range of from to 200 C. to an image-receiving layer, whereby at the exposed areas the image-producing reducing agent is converted to a non-transferable compound, (2) bringing the exposed layer into contact with an image-receiving layer which contains a compound capable of reacting with the reducing agent transferred from the unexposed areas to form colored products and (3) heating the layers while in contact at a temperature in the range of from 80 to 1200 C. to produce a visible image in the image-receiving ayer.

The light-sensitivity of the layer is highly increased by the addition of at least one of the guanidine or biguanide derivatives.

Compounds of the following formula have proved to be particularly suitable:

wherein R =hydrogen or aryl, especially a radical of the phenyl series, the aryl group or especially the phenyl ring may, in any position but preferably in the ortho or para position, be substituted by preferably alkyl or alkoxy, both with preferably up to 3 C-atoms, halogen, such as fluorine, chlorine, bromine or iodine, but also by other substituents such as carboxyl, esterified carboxyl, sulfo, sulfonamide or esterified sulfo groups;

R =aryl, preferably, a radical of the phenyl series, where the aryl group or the phenyl ring may be substituted as described under R or a group of the formula NHR where R has the meaning stated above.

o-Tolylbiguanide, 1,3-diphenylguanidine and 1,3-di-otolylguanidine are particularly suitable.

Acylacetonitrile derivatives of the following general formula are suitable as image-producing reducing agents transferable in the temperature range from 80 to 200 C.:

where R =(1) alkyl with up to C-atoms, preferably methyl or ethyl, (2) alkoxy or alkoxycarbonyl with preferably up to 5 C-atoms, (3) aryl or substituted aryl, especially a radical of the phenyl series, which may be substituted for example with alkyl or alkoxy, both with preferably not more than 3 C-atoms, or halogen, such as fluorine, chlorine, bromine or iodine as well as by other substituents like esterified carboxyl, or (4) aralkyl, especially benzyl or phenylethyl;

R 1) aryl, in particular a group of the phenyl series, which may be substituted, for example, by halogen, such as fluorine, chlorine, bromine or iodine; phenyl, phenoxy, alkyl or alkoxy, both preferably with not more than 3 C-atoms, or (2) heterocyclic groups, such as furyl, pyridyl or thienyl.

Suitable compounds are contained in Table 1:

TABLE 1 Nitrlle number 11 -0 0- 3-methylphenyl.-

-. 4-methylphenyl;

.- t-phenylphenyl.

4-chlorophenyl.

8 --do 3,4-dimethoxyphenyl;

4-bromopheny 2,5-dichlorophenyl.

4-iodophenyl.

3-chloropheuyl.

3,4,5-trimethoxyphenyl.

henyl.

4 where R! wlol or R -QR R and R together may also represent the members necessary for completing of an isoor heterocyclic ketomethylene ring; these can be those rings that are conventional in cyanin chemistry such as those of the rhodanin series, like 3-ethylrhodanine, 3-allylrhodanine and 3-cyclohexylrhodanine, those of the 2-thio- 2,4-oxazolidindione series like 3-ethyl-2-thio-2,4oxazolidindione, those of the thiohydantoin series like 1,3- dimethyl-Z-thiohydantoin and 1 methyl-3-phenyl-2- thiohydantoin, those of the barbituric acid or thiobarbituric acid series like 1,3-diethyl-thiobarbituric acid and 1,3-diphenylthiobarbituric acid, those of the isoxazolone, oxindole, 2-thio-2,S-thiazolidindione, or the 2,4- imidazolidindione series or the ketomethylene compounds of the following structural formulae:

R =hydrogen or nitro R =a saturated or olefinically unsaturated aliphatic group with preferably not more than 6 C-atoms, which can be substituted with, for example, phenyl, hydroxyl, halogen, such as chlorine or bromine, amino, carboxyl, sulfo or aryl, such as phenyl or naphthyl;

Z Z =hydr0gen, alkyl preferably with not more than 3 C-atoms or alkoxycarbonyl preferably with not more than 4 C-atoms; Z and Z may also represent methylene groups forming part of a 5- or 6-membered ring;

X=oxygen or sulfur.

The heterocyclic rings containing aryl groups may, if desired, contain further substituents such as further alkyl groups preferably with not more than 3 C-atoms, such as methyl or ethyl, halogen such as chlorine, bromine or iodine or the trifluoromethyl group, hydroxyl, alkoxy preferably with not more than 3 C-atoms such as methoxy or ethoxy, alkoxycarbonyl, hydroxyalkyl, alkylthio, aryl such as phenyl or aralkyl such as benzyl, amino, substituted amino and so on.

For example, the following compounds are suitable:

The dyes to be used in accordance with the invention are easily obtained by condensation of ketomethylene compounds with corresponding aldehydes in solvents such as alcohol, pyridine or glacial acetic acid, if desired with addition of a base like triethylamine or piperidine.

The preparation of the dyes A 7 and A 26 is described in detail below:

Dye A 7 2.5 ml. of a 50% aqueous solution of sodium hydroxide were added to a solution of 4.0 g. o-hydroxycinnamicaldehyde-O-acetic acid and 1.0 g. cyclohexanone in 50 ml. alcohol. After standing 30 minutes at room temperature, the mixture was acidified with dilute hydrochloric acid, the dye was removed by suction and recrystallized from chloroform/methanol. 2.4 g., M.P. 264-266 C. (under decomposition) Dye A 26 2.0 g. of 1,3-diethylthiobarbituric acid were heated 30 minutes on the steam bath with 1.7 g. 4-dimethylaminocinnamicaldehyde in 50 ml. alcohol. After cooling, the dye was removed by suction and recrystallized from chloroform/methanol. 3.3 g., M.P. 2l2-214 C.

(B) Halogen and/or selenium containing polymethin dyes of the general formulae:

Ill AIliD 'm :1 Hal k CH=CH AnionH N( L n Hal III Hal IV Hal Hal Z a n -Qon=c-fi-h=orr an V io I n N u T AnlonH where Hal=Cl, Br or I;

R =(1) a saturated or unsaturated aliphatic group with preferably not more than 6 C-atoms which may contain substituents such as halogen or phenyl, hydroxyl, amino, carboxyl, sulfo, sulfamoyl, carbamoyl, alkoxycarbonyl, alkoxy, carboxyalkyl, sulfato or thiosulfato groups; (2) cycloalkyl such as cyclohexyl; or (3) aryl, especially a group of the phenyl series;

R =hydrogen, alkyl with preferably not more than 3 C-atoms, aryl, such as phenyl, or cycloalkyl, such as cyclohexyl;

R R =the same or different, namely hydrogen or bydroxyl, where however at least one of R and R is a hydroxyl group;

R =hydrogen, alkyl or alkoxy with preferably not more than C-atoms, halogen, especially chlorine, bromine or iodine, a trifluoromethyl group or aryl, especially a phenyl group;

R =aryl such as phenyl, a heterocyclic ring such as thienyl or furyl which may also be substituted;

X =the ring members required for completing a benzene or naphthalene ring containing-if Y is different from Seat least one halogen such as chlorine, bromine or iodine or a trifluoromethyl group, e.g. for the completion of a S-iodobenzthiazole, 5-iodobenzselenazole, 6-iodobenzthiazole, 6 bromobenzthiazole, 5 broxnobenzoxazole or a S-iodobenzoxazole ring and so on;

Z Z =hydrogen, alkyl with preferably not more than 3 C-atoms or alkoxycarbonyl groups with preferably not more than 4 C-atoms; Z and Z can also be methylene groups necessary for completing a 5- or 6-membered ring;

Y=O, S, Se, -CH=CH, N-alkyl, the alkyl having preferably up to 5 C-atoms, N-aryl, in particular N- phenyl;

Anion=any anion such as halide, e.g. chloride, bromide or iodide, perchlorate, sulfate, methyl sulfate, p-toluene sulfate; the anion is omitted if R contains an acid group in the anionic form so that a betaine is present;

n=0, 1 or 2;

D=the members of a ring necessary for completing an isoor heterocyclic ketomethylene ring; these are the ketomethylene rings usual in cyanine chemistry, such as those of the rhodanine series like B-ethylrhodanine, 3-allylrhodanine, 3-cyclohexylrhodanine, those of the 2-thio-2,4-oxazolidindione series like 3-ethyl-2-thio-2,4- oxazolidindione, those of the thiohydantoine series like l,3-dimethyl-2-thiohydantoine, l-methyl 3 phenyl-2- thiohydantoine, those of the barbituric acid or thiobarbituric acid series like 1,3-diethyl-thiobarbituric acid, l,3-diphenylthiobarbituric acid, those of the isoxazolone, oxinclole, 2-thio-2,5-thiazolidindione, 2,4-imidazolidindione series or the ketomethylene rings indicated by the following structural formulae:

Q=the members required for completion of 5- or 6-membered heterocyclic ring; the heterocyclic group may contain a fused benzene or naphthalene ring and further substituents; these are the heterocyclics conventional in cyanine chemistry such as those of the thiazole series (e.g. thiazole, 4-methylthiazole, S-methylthiazole, 4,5- dimethylthiazole, 4-phenylthiazole, S-phenylthiazole, 4,5-diphenylthiazole, etc.), those of the benzthiazole series (e.g. benzthiazole, 4-chlorobenzthiazole, 5-chlorobenzthiazole, 6-chlorobenzthiazole, 7-chlorobenzthiazole, fi-bromobenzthiazole, S-iodobenzthiazole, 6-iodobenzthiazole, 4-methylbenzthiazole, S-methylbenzthiazole, -methylbenzthiazole, 5,6-dimethylbenzthiazole, 4-phenylbenzthiazole, 5-phenylbenzthiazole, 6-phenylbenzthiazole, S-hydroxybenzthiazole, 6-hydroxybenzthiazole, 4-methoxybenzthiazole, S-methoxybenzthiazole, 6-methoxybenzthiazole, S-ethoxybenzthiazole, 6-ethoxybenzthiazole, 5,fi-dimethoxybenzthiazole, 5,6- methylenedioxybenzthiazole, 5 diethylaminobenzthiazole, 6-diethylaminobenzthiazole, S-carboxybenzthiazole, S-sulfobenzthiazole, tetrahydrobenzthiazole, 7-oxotetrahydrobenzthiazole etc.), those of the naphthothiazole series (e.g. naphtho(1,2-d)thiazole, naphtho(2,ld) thiazole, 5-methoxynaphtho(2,1-d) thiazole, 5-ethoxynaphtho(2,l-d)thiazole, 7 methoxynaphtho(2,l-d)thiazole, 8-methoxynaphtho(l,2-d)thiazole etc.), those of the selenazole series (for example 4-methylselenazo1e or 4-phenylselenazole), those of the benzoselenazole series (for example benzoselenazole, 5-chl0robenzo selenazole, 5,6-dimethylbenzoselenazole, S-hydroxybenzoselenazole, S-methoxybenzoselenazole, tetrahydrobenzoselenazole etc.), those of the naphthoselenazole series (for example naphtho(l,2-d)selenazole or naphtho(2,1-d)selenazole), those of the oxazole series (for example oxazole, 4-methyloxazole, 4-phenyloxazole, 4,5-dipheny1oxazole etc.), those of the benzoxazole series (for example benzoxazole, 5-chlorobenzoxazole, fi-chlorobenzoxazole, 5,6-dimethylbenzoxazole, S-phenylbenzoxazole, S-hydroxybenzoxazole, S-methoxybenzoxazole, S-ethoxybenzoxazole, 6-dialkylarninobenzoxazole, S-carboxybenzoxazole, 5-sulfobenzoxazole, 5-sulfonamidobenzoxazole, 5 p carboxyvinylbenzoxazole etc.), those of the naphthoxazole series (for example naphtho( 1,2 d)oxazole, naphtho( 2,1 d)oxazole or naphtho(2,3-d)oxazole), those of the imidazole series (for example l-methylimidazole, 1-ethy1-4-phenylimidazole, 1-butyl-4,S-dimethylimidazole etc.), those of the benzimidazole series (for example l-methylbenzimidazole, 1-butyl-4-methylbenzimidazole, 1-ethyl-S,6-dichlorobenzimidazole, 1-ethyl-S-trifluoromethylbenzimidazole etc.), those of the naphthimidazole series (for example 1-methylnaphth0(l,2-d)imidazole or l-ethylnaphtho(2,3-d)imidazole), those of the 3,3-dialkylindolenine series (for example 3,3-dimethylindolenine, 3,3, S-trimethylindolenine, 3,3-dimethyl 5 methoxyindolenine etc.), those of the 2-pyridine series (for example pyridine, 3-methylpyridine, 4-methylpyridine, S-methylpyridine, 6-methylpyridine, 3,4-dimethylpyridine, 3,5- dimethylpyridine, 3,6-dimethy1pyridine, 4,5-dimethylpyridine, 4,6-dimethylpyridine, 4-chloropyridine, S-chloropyridine, 6-chloropyridine, 3-hydroxypyridine, 4-hydroxypyridine, S-hydroxypyridine, 6-hydroxypyridine, 3-phenylpyridine, 4-phenylpyridine, 6-phenylpyridine etc.), those of the 4-pyridine series (for example Z-methylpyridine, S-methylpyridine, 2,3-dimethylpyridine, 2,5-dirnethylpyridine, 2,6-dimethylpyridine, 2-chloropyridine, 3-chloropyridine, 2-hydroxypyridine, 3-hydroxypyridine etc.), those of the 2-quinoline series (for example quinoline, 3-methylquinoline, S-methylquinoline, 7-methylquinoline, S-methylquinoline, 6-chloroquinoline, 8 chloroquinoline, 6 methoxyquinoline, fi-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, 5-oxo-5,6,7,8-tetrahydroquinoline etc.), those of the 4-quinoline series (for example quinoline, 6-methoxyquinoline, 7-methylquinoline, 8-methylquin0line etc.), those of the isoquinoline series (for example isoquinoline or 3,4-dihydroisoquinoline), those of the thiazoline series (for example thiazoline, 4-methylthiazoline etc.), as well as those of the pyrroline, tetrahydropyridine, thiadiazole, oxadiazole, pyrimidine, triazine or benzthiazine series. The heterocyclic rings and aryl groups may be further substituted in any way desired, for example by further alkyl groups with preferably not more than 3 C-atoms, such as methyl or ethyl, halogen such as chlorine, bromine or iodine or the trifluoromethyl group, hydroxyl, alkoxy with preferably not more than 3 C-atoms, such as methoxy or ethoxy, hydroxyalkyl, alkylthio, aryl, such as phenyl, or aralkyl such as benzyl, amino, substituted amino and so on.

For example, the following compounds are suitable:

acetic acid with the addition of a base such as triethylamine or piperidine.

We now describe in detail the preparation of the compounds B 15 and B 23. The other compounds are obtained in a similar way.

Compound B 15 2.0 g. of 1,3-diethyl-thiobarbituric acid were refluxed for minutes with 3.7 g. 3,5-diiodo-4hydroxy-benzaldehyde in 30 ml. glacial acetic acid with the addition of 3 ml. piperidine. The mixture was cooled, the dye removed by suction and recrystallized from methanol. 3.6 g. of the dye of MP. 248 C. (decomposed) were obtained.

Compound B23 4.0 g. of 2-methyl-3-ethyl-benzosolenazole tosylate was heated on a steam bath for minutes with 3.7 g. 3,5- diiodo-4-hydroxybenzaldehyde in 50 m1. alcohol with addition of 2 ml. triethylamine. After only a short time the dye precipitates. The mixture was cooled, the dye removed by suction, washed with alcohol and recrystallized from dimethylformamide. 3.7 g., M.P. 237 C. (decomposed).

The dyes of Formula H may also, in the case of this preparation, be present in the quinoid form as a result of the acid corresponding to the anion being split 01f (cf. F. M. Hamer: The Cyanne Dyes and Related Compounds, 1964, page 592). This is, however, Without importance in relation to their effectiveness for the purpose of the invention.

(C) Merocyanines of the general formula:

wherein R =(1) a saturated or unsaturated aliphatic group with preferably not more than 6 C-atoms, which may be substituted, for example, with halogen or phenyl, hydroxyl, amino, carboxyl, sulfo, sulfamoyl, carbamoyl, carboxyalkyl, alkoxycarbonyl, sulfato or thiosulfato groups, (2) cycloalkyl such as cyclohexyl; or (3) aryl, especially a group of the phenyl series;

R =hydrogen, alkyl with up to 4 C-atoms, hydroxyl,

alkoxy with up to 4 C-atoms, such as methoxy or ethoxy, or aryl such as phenyl;

R =the meaning given above;

X =oxygen or sulfur;

n =0, 1 or 2;

m=4, 5 or 6;

Q =the ring members required for completing a 5- or 6- membered heterocyclic ring; the heterocyclic group can contain a fused benzene or naphthalene ring and further substituents; these include the heterocyclics usual in cyanine chemistry such a those of the thiazole series (for example, thiazole, 4-methylthiazole, 5 methylthiazole, 4,5-dimethylthiazole, 4-phenylthiazole, S-phenylthiazole, 4,5-diphenylthiazole etc.), those of the benzthiazole series (for example, benzthiazole, 4 chloro benzthiazole, S-chlorobenzthiazole, 6 chlorobenzthiazole, 7-chlorobenzthiazole, 6-bromobenzthiazole, 5- iodobenzthiazole, fi-iodobenzthiazole, 4 methylbenzthiazole, S-methylbenzthiazole, 6-methylbenzthiazole, 5,6- dimethylbenzthiazole, 4-phenylbenzthiazole, 5 phenylbenzthiazole, G-phenylbenzthiazole, 5 hydroxybenzthiazole, 6-hydroxybenzthiazole, 4 methoxybenzthiazole, S-methoxybenzthiazole, 6-methoxybenzthiazole, 5 ethoxybenzthiazole, 6-ethoxybenzthiazole, 5,6-dimethoxybenzthiazole, 5,6-methylenedioxybenzthiazole, 5 diethylaminobenzthiazole, 6-diethylaminobenzthiazole, S-carboxybenzthiazole, 5-su1fobenzthiazole, tetrahydrobenzthiazole, 7-oxotetrahydrobenzthiazole etc.), those of the naphthothiazole series (for example, naphtho(1,2-d) thiazole, naphtho(2,1-d)thiazole, 5 methoxynaphtho- (2,1-d)thiazole, S-ethoxynaphtho(2,1-d)thiazole, 7-methoxynaphtho(2,l-d)thiazole, 8 methoxynaphtho(1,2- d)thiazole etc.), those of the selenazole series (for example, 4-methylselenazole or 4-phenylselenazole), those of the benzoselenazole series (for example, benzoselenazole, S-chlorobenzoselenazole, 5,6-dimethylbenzoselenazole, S-hydroxybenzoselenazole, S-methoxybenzoselenazole, tetrahydrobenzoselenazole, etc.), those of the naphthoselenazole series (for example, naphtho( 1,2- d)selenazole or naphtho(2,l-d)selenazole), those of the oxazole series (for example, oxazole, 4-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole etc.), those of the benzoxazole series (for example, benzoxazole, S-chlorobenzoxazole, 6-chlorobenzoxazole, 5,6-dimethylbenzoxazole, 5-phenylbenzoxazole, 5 hydroxybenzoxazole, S-methoxybenzoxazole, 5-ethoxybenzoxazole, 6-dialkylaminobenzoxazole, 5 carboxybenzoxazole, 5 sulfobenzoxazole, 5 sulfonamidobenzoxazole, 5-,B-carboxyvinylbenzoxazole etc.), those of the naphthoxazole series (for example, naphtho(1,2 d)oxazole, naphtho- (2,1-d)oxazole or naphtho(2,3-d)oxazole), those of the imidazole series (for example, l-methylimidazole, 1-ethy1-4-phenylimidazole, l-butyl 4,5 dimethylimidazole etc.), those of the benzimidazole series (for example, l-methylbenzimidazole, 1 butyl-4-methylbenzimidazole, 1-ethy1-5,6-dichlorobenzimidazole, l-ethyl-S- trifluoromethylbenzirnidazole etc.), those of the naphthimidazole series (for example, 1-methylnaphtho(l,2- d)imidazole or l-ethylnaphtho(2,3-d)imidazole), those of the 3,3-dialkylindolenine series (for example, 3,3-dimethylindolenine, 3,3,5 trimethylindolenine, 3,3 dimethyl-S-methoxyindolenine etc.), those of the 2-pyridine series (for example, pyridine, 3-methylpyridine, 4- methylpyridine, S-methylpyridine, 6 methylpyridine, 3,4-dimethylpyridine, 3,5 dimethylpyridine, 3,6 dimethylpyridine, 4,5-dimethylpyridine, 4,6-dimethylpyridine, 4-chloropyridine, S-chloropyridine, 6 -chloropyridine, 3-hydroxypyridine, 4-hydroxypyridine, S-hydroxypyridine, 6-hydroxypyridine, 3-phenylpyridine, 4-phenylpyridine, 6-phenylpyridine, etc.), those of the 4-pyridine series (for example, Z-methylpyridine, S-methylpyridine, 2,3-dimethylpyridine, 2,5 dimethylpyridine, 2,6-dimethylpyridine, 2-chloropyridine, 3 chloropyridine, 2-hydroxypyridine, 3-hydroxypyridine etc.), those of the Z-quinoline series (for example, quinoline, 3- methylquinoline, 5 methylquinoline, 7 methylquinoline, -8-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6 ethoxyquinoline, 6- hydroxyquinoline, S-hydroxyquinoline, 5 oxo-5,6,7,8- tetrahydroquinoline etc.), those of the 4-quinoline series (for example, quinoline, 6-methoxyquinoline, 7- methylquinoline, S-methylquinoline etc.), those of the isoquinoline series (for example, isoquinoline or 3,4-dihydroisoquinoline), those of the thiazoline series (for example, thiazoline, 4-methylthiazoline etc.), as well as those of the pyrroline, tetrahydropyridine, thiadiazole, oxadiazole, pyrimidine, triazine or benzthiazine series.

The heterocyclic rings can be additionally substituted in any way desired, for example, with further alkyl groups with preferably not more than 3 C-atoms, such as methyl or ethyl, halogen such as chlorine, iodine or bromine, trifiuoromethyl, hydroxy, alkoxy with preferably not more than 3 C-atoms, such as methyl or ethyl, halogen such as chlorine, iodine or bromine, trifiuoromethyl, hydroxyl, alkoxy with preferably not more than 3 C-atoms, such as methoxy or ethoxy, hydroxyalkyl, alkylthio, aryl such as phenyl, or aralkyl such as benzyl, amino, substituted amino and so on.

For example, the following compounds are suitable:

)=CHC H N 2.

HOOCOH=CH S I S O I )5 II CHCH- I? CzH The light-sensitive layers preferably contain at least The concentration largely depends on the requirements of one sensitizer in an amount of 10-300 mg./m. one or 70 the particular reproduction process.

more of the guanidine derivatives in an amount of 10-500 Particularly suitable combinations of the sensitizers mg./m. and one or more image-producing reducing with the image-producing reducing agents and the guaniagents in an amount of 002-05 g./m. These concendine derivatives of the inventions can be found by simple tration ranges have proved suitable although, of course, tests. In order to achieve optimum results the choice of it is also possible to operate outside these concentrations. 75 solvent and of the binding agent used in the preparation 36 of the light-sensitive emulsion is also of some importance. The best combination of components for each purpose can be discovered by the usual experiments familiar to anyone skilled in the art.

In order to prepare the light-sensitive coating, guanidine derivatives, sensitizers and image-producing reducing agents can be suspended or dissolved in solvents and, mixed with a binding agent, coated onto the layer support.

In the preparation of the light-sensitive casting solution, it is advantageous to dissolve the components in the solvent in the ordersensitizer-reducing agent-guanidine derivative. This applies particularly in the use of sensitizers that are attacked by any strongly basic medium and with which worse results can be obtained on adding the components in the order sensitizer-guanidine derivative-reducing agent or guanidine derivative-sensitizer-reducing agent.

As binding agents for the light-sensitive emulsion the usual natural or synthetic film-forming polymers are suitable such as proteins, especially gelatin, cellulose derivatives, especially cellulose ethers, cellulose esters or carboxymethylcellulose, alginic acid and its derivatives, starch ethers or gallactomannans, as well as polyvinylalcohol, polyvinylpyrrolidone, polyvinylchloride, copolymers of vinylchloride and vinylacetate, polyvinylacetate or completely or partly hydrolyzed polyvinylacetate or copolymers of vinylacetate, mixed polymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters, polyethylene etc.

The light-sensitive layer can be used as self-supporting films or applied to a layer support. Suitable supports are, for example, paper, especially baryta-coated or laminated paper. Cellulose esters, for example cellulose triacetate, polyesters, especially those based on ethyleneterephthalate, glass etc.

The image-receiving material consists preferably of an image-receiving layer which is applied to a suitable support. The same substances are, in general, suitable both as binding agents for the image-receiving layer and also the supports. Such substances have been described above as binding agents for the light-sensitive material.

In choosing a binder for the light-sensitive layer and the image-receiving layer, care should be taken that the coatings do not adhere together on heating. These difficulties, are, however, known from other transfer processes such as the silver salt diflusion process or the heat development process and can be overcome without trouble using the experience gained in these known fields.

The image-receiving layer contains compounds that, under the conditions of the process of the invention, should not be sensitive or should be only very slightly sensitive to light and react with the transferred imageproducing compounds to form colored products. A number of compounds have proved suitable for this purpose. These compounds belong chemically to the most different classes so that a uniform classification is not possible. Suitable compounds and suitable combinations of an imageproducing compound which is incorporated in the lightsensitive layer coating, and of the reaction partner for the reaction in the image-receiving layer which yields the image dye, can, however, be easily found by simple laboratory tests customarily employed in the art. Thus, the two reaction partners must react, on brief heating for a few seconds at a temperature of from 80 to 200 C., to give a stable image dye. A second test is then required for the selection of suitable image-producing compounds in order to find out whether the image-producing compound reacts rapidly enough on exposure in the presence of the guanidine derivative and the sensitizer so that heating of the mixture thus exposed together with the reaction partner of the image-receiving emulsion produces no more colored compound.

As reaction partner in the image-receiving layer for the image-producing compounds, heavy metal compounds are suitable, especially of metals of Groups IIIa, Na and Va and Groups Ib, IIb, VIb and VIII of The Periodic Table of the Elements, for example, compounds of the heavy metals: cadmium, mercury, iron, cobalt, nickel, copper, silver, gold, bismuth or thallium. Salts of these metals with long chain aliphatic carboxylic acids are particularly suitable, such as nickel stearate, cobalt palmitate, iron stearate, the addition compound of bismuth nitrate with amines, for example triethanolamine. Silver compounds have proved particularly suitable which, under the conditions of the copying process of the invention, are largely insensitive to light, for example the silver salts described in UK. patent specification No. 1,111,492 of aliphatic carboxylic acids with a thioether group or silver salts of long chain fatty acids, such silver behenate, silver palmitate, silver stearate etc.

With the use of the above mentioned heavy metal compounds brown to black copies are generally obtained. The image consists of the metal in question and/or a reaction product of the transferred image-producing compound.

The image-receiving layers may further contain additives that have a favourable efiect on the color tone, con trast, stability etc. of the copy. Such image-receiving layers are already known' and described, for example, in DAS 895,101, 1,003,577, 1,159,758, 1,004,043 and 1,165,410, in Netherlands Pat. No. 277086 and in Belgian Pat. Nos. 614064 and 609-057.

The image-receiving layers may also contain white pigments, such as zinc oxide or silicon dioxide or titanium dioxide as fillers to improve the whiteness and influence the adhesive tendency and terpene resins and organic acids to improve the storage stabiilty. Such image-receiving coatings are described in US. Pat. Nos. 3,074,809 and 3,107,174.

The color tone of the resulting images can be influenced, for example, by compounds of the 1-(2H)-phthalazinone series; such toners are described in US. Pat. Nos. 3,080,- 254 and 3,446,648.

Phthalimide and its derivatives can also be used for this purpose. Additives which accelerate the reduction reaction in the image-receiving layer have also been found advantageous. For example, sterically hindered phenols, such as 2,6-di-tert-butyl-p-cresol, are suitable for this purpose. Such compounds are described in U.S.'Pat. No. 3,218,166. Moreover the tone and density of the image can be improved by certain metal salts, such as copper-II-stearate. Such metal ion image-intensifiers and their use are described in DAS 1,572,209.

For exposure of the light-sensitive layer coatings of the invention, light sources customarily employed in the art, such as mercury lamps, iodine quartz lamps or incandescent lamps can be used. The spectral sensitivity of the light-sensitive material depends on the nature of the sensitizing dye used and on the combination of dye and reducing agent.

The exposure can be carried out by contact, optical or reflex methods.

The transfer of the image-producing compounds from the unexposed areas of the light-sensitive emulsions to the image-receiving coating occurs at temperatures of from to 200 C. The heating can be brought about, for example, by conducting the exposed light-sensitive layer while in contact with the image-receiving layer over hot plates or rollers or by uniform exposure with infrared light. The most favourable temperature and heating time of course depends on the nature of the image-producing compound; it can be discovered by a few simple experiments.

According to one modification of the material of the invention, it is also possible to combine the image-receiving layer and the light-sensitive layer on on layer support. In this case it is necessary to use a transparent support to which first the image-receiving layer, for example a layer which contains silver behenate dispersed in a copolymer of styrene and isobutylene, is applied and to apply the light-sensitive layer on to the image-receiving layer, for

example an ethyl-cellulose coating which contains the sensitizer, the guanidine derivative and the reducing agent.

By combination of the photo-reducible dyes for use in accordance with the invention with those described, for example, in the US. Pat. No. 3,094,417 such as erythrosin, the sensitivity of these light-sensitivity layers can be increased or widened to other regions of the spectrum in a way that depends on the absorption of the sensitizers. In such combinations also, the addition of the guanidine derivatives of the invention yields an increase in the sensitivity.

EXAMPLE 1 Light-sensitive material: A semitransparent paper support was coated with the following solution:

Dye according to Table 2 -mg 6 2-(p-chlorophenyl)-acetoacetonitrile mg 125 o-Tolylbiguanide m 30 Ethylacetate ml 70 Methanol, and ml Ethylcellulose g 2.5

The layer was dried in the usual way. For comparison, a light-sensitive coating not containing o-tolylbiguanide was prepared in the same way.

The image-receiving material was prepared by grinding in a ball mill, coating on to a paper support and drying. The dried layer contained about 0.2 g. silver per m in the form of the silver salt.

Treatment The light-sensitive material was exposed behind a /5 step wedge for 5 minutes to 1000 watt iodine quartz lamp at a distance of 30 cm.

Thereupon the exposed layer was brought into contact with the image-receiving layer and heated for 10 seconds at a temperature of 125 C. or treated in a commercial heat-developing apparatus. Brownish-black copies of the wedge were obtained. The increase in sensitivity obtained by the addition of the guanidine derivative can be seen from the diflerence between the step numbers of the sample and of the guanidine-free control sample. The results are shown in the following table:

TAB LE 2 42-wedge steps of the sample With l Without 1 Dye number esQmUceeeoomeaqqmeucnoommuu QHQOQHQHQQHHQQQQNOOQ TABLE 2Contlnued 45-wedge steps of the sample- Dye number With 1 Without l 4 0 2 o a 0 3 0 s o a o 4 o 2 0 5 0 e 0 5 0 a o 1 o 1 0 a 0 5 0 7 1 7 1 2 0 2 0 a o 4 0 2 0 2 0 4 0 a 0 6 0 3 0 3 o a 0 5 0 7 o 1 o-Tolylblguanide additive.

EXAMPLE 2 A light-sensitive material was prepared as in Example 1, using a solution of the following composition:

Dye according to Table 3 mg 6.0 Acylacetonitrile derivative according to Table 3 mg 125.0 Guanidine derivative according to Table 3 mg 30.0 Ethylcellulose e 2.5 Ethyl acetate ml 75.0

The same image-receiving material was used as in Example 1. The treatment was as described in Example 1. The results of the sensitometric tests are shown in the following table:

TABLE 3 Acyl- Number ecetoof [2- nitrile wedge Dye number N o. Guanidine derivative steps 7 1,3-diphenylguanldine 6 7 1,3-di-o-tolylguanidine 7 7 d 8 8 10 6 6 7 6 7 1,3-di-o-tolylguanldlne 8 7 1,3-diphenylguanidine 7 5 o-tolylbig'uanidine 8 16 do 6 14 do 7 EXAMPLE 3 A light-sensitive material was prepared by dipping a semi-transparent paper support into a solution of the following composition and drying at room temperature:

The light-sensitive material was exposed in reflex in contact with an original sheet written on both sides in a commercial reflex copying device provided with a 1000 w. iodine quartz lamp as light source. The exposed layer was then heated in contact with an image-receiving layer for 37 10 seconds at 130 C. A black copy of the original in the image-receiving layer was obtained. The image-receiving material was prepared in the following way;

was ground overnight in a ball mill and after adding 1.5 g. 2,6-dicyclohexyl-p-cresol applied to a paper support and dried. The silver applied amounted to 0.3 g./m. in the form of the silver salt. The results of sensitometric tests are given in the following table. As reflex copying time the minimum exposure required for the production of saturated blacks and clear whites is quoted. The spectral sensitivity was determined by exposing through a set of color filters of the following transmissivities:

350 nm., 390 nm., 405 nm., 435 nm., 480 nm., 505 nm., 515 nm., 540 nm., 550 nm., 570 nm., 590 nm., 605 nm. The light-sensitive material was exposed for to 30 minutes, depending on the dye, behind the filters to an iodine quartz lamp of 1000 watts at a distance of 30 cm.

Then the exposed material was placed in contact with the image-receiving layer described in Example 3 and treated in a commercial heat developing apparatus.

TABLE 4 Reflex copying, Spectral time/sec. sensitivity/nm.

In tests with light-sensitive layers which had been prepared in a similar way but without addition of the biguanide, no copies with clear whites were obtained or only copies with poor contrast and much lower sensitivity.

EXAMPLE 4 By combining suitable dyes it is possible to produce emulsion coatings sensitive to several regions of the spectrum, For this purpose, erythrosine, which is sensitive at 540 nm., can be employed with advantage as a component dye. In order to do this, for example, the dyes, 2-(pchlorophenyl)-acetoacetonitrile and o-tolylbiguanide were added, in the amounts given in Table 5, to the casting solution which contained 2,5 g. ethylcellulose in 75 ml. ethylacetate. The subsequent treatment was carried out as in Example 3.

TABLE 5 0 T R S spectrlal sensitivity (nm.)

Mg. Dye number 0 T R S 4 mg. A32 plus 4 mg. B11 180 60 12 405, 480,515,590 4 mg. A32 plus 4 mg. A12 180 60 15 405, 480, 515, 590 4 mg. erythroslne plus 4 mg. A8 180 30 12 405, 480, 515, 540 6 mg. erythrosine plus 6 mg. A32. '240 45 18 405, 480,515, 540 3 mg. erythrosine plus 3 mg. B33 30 10 0, 590, 605 4 mg. erythrosine plus 4 mg. 1332 60 13. 5 540, 590, 605 4 mg. erythrosine plus 4 mg. 1323... 180 30 15 540, 590, 605 4 mg. B33 plus 4 mg. B11 180 60 15 540, 590, 605 4 mg. B33 plus 4 mg. A12 125 30 9 405, 480, 590, 605 4 mg. B33 plus 4 mg. A12 180 60 12 405,480,590, 605 4 mg. B33 plus 4 mg. B16.-. 125 30 12 480, 590, 605 3 mg. B33 plus 3 mg. A32 125 30 10. 5 405, 480, 0, 605 3 mg. B32 plus 3 mg. erythroslne plus 3 mg. A32 180 45 15 405, 480, 515-605 4 mg. erythrcsine plus 4 mg. B33

plus 4 mg. A32 180 90 9 405, 480, 515-505 2 mg. erythrosine plus 2 mg. B

plus 2 mg. A32 12.5 30 10.5 405,480,515-605 4 mg. B11 plus 4 mg. A32 plus 4 mg. erythrosine 180 90 9 405, 480550 10mg. B41 plus 10 mg. B43 plus 10 mg. B49 118 38 15 If the guanidine derivative is omitted the layers show a considerable loss of sensitivity and flattening of the gamma value.

What is claimed is:

1. A process for producing photographic images comprising exposing to image-forming light a light-sensitive layer containing an image-producing compound capable of being transferred from said layer and being characterized as readily forming a nontransferable product upon exposure, said exposure being for a time sufficient to form non-transferable portions of said image-producing compound in exposed areas, placing the exposed layer in contact with a receiving layer of material containing a heavy metal compound which reacts with transferred image-producing compound to form colored compounds, heating of the layers in contact with each other at a temperature of between 80-200 C. to transfer the image-forming compound in the unexposed areas to the receiving layer and forming a visible image in the receiving layer, wherein the improvement comprises the image-producing transferable compound is an acylacetonitrile derivative having the following formula:

wherein R represents alkyl with up to 5 carbon atoms;

alkoxy with up to 5 carbon atoms;

aryl or aralkyl;

R represents aryl or a heterocyclic group of the class consisting of furyl, pridyl or thienyl;

the said transferable compound is exposed in the presence of a sensitizing dye from the class of the neutrostyryl dyes, the merocyanines or a cyanine dye containing a halogen substituted benzine ring or a heterocyclic ring derived from selenazol and a compound of the guanidine or biguanide series.

2. The process of claim 1, wherein the guanidine derivative has the following formula:

where R 1=hydrogen or aryl R =aryl or a residue of the formula NHRI 3. The process of claim 1, wherein the neutrostyryl dye is selected from those having the following formulae:

where having the following formulae:

Anlr1(') J 'gm in L II Hal CH=CH R" Aniom') m R" Hal 1.

III Hal l l B" Hal IV Hal Hal Zl za R -CH=& !=CH -Rn I I-ilal R" A Hal N Rl g R Anlon -CH=CH XI IL L/ l where Hal=Cl, Br or I R -=0) a saturated or unsaturated aliphatic group,

(2) cycloalkyl or (3) aryl R =hydrogen, alkyl, aryl or cycloalkyl R R hydrogen or hydroxyl, where however at least one of the group stands for hydroxyl R =hydrogen, alkyl or alkoxy, halogen, trifiuoromethyl or aryl R =aryl or a heterocyclic ring X =the ring members required for completing a benzene or naphthalene ring which contains-if Y is different from Se-at least one halogen or a trifuoromethyl group Z Z =hydrogen, alkyl or alkoxycarbonyl; Z and 2 can also stand for methylene groups required to complete a 5- or 6-membered ring Y=0, S, Se, -CH=CH, N-alkyl, N-aryl n=0, 1 or 2 D=the ring members required to complete an isoor heterocyclic ketomethylene ring Q=the ring members required to complete a 5- or 6- membered heterocyclic ring.

5. The process of claim 1, wherein the merocyanine has the following formula:

where R =(1) a saturated or unsaturated aliphatic group,

(2) cycloalkyl, (3) aryl R"=CN, COR, N (R )2, COOR R =R OR N(R) or -N (om).-

R" and R =the ring members required for completion of an isoor heterocyclic ketomethylene ring R =hydrogen, alkyl with not more than 4 C-atoms,

hydroxyl, alkoxy with not more than 4 C-atoms or aryl R =a saturated or olefinically unsaturated aliphatic X =0xygen or sulfur m=4, 5 or 6 Q =the ring members required for completing a 5- or 6-membered heterocyclic ring.

6. A light-sensitive photographic material wherein a transferable light-sensitive compound is converted upon exposure to light to provide a non-transferable product in the exposed areas and a transferable compound in the unexposed areas, said photographic material comprising on a support at least one light-sensitive layer containing as the image-producing transferable compound an acyl acetonitrile derivative having the following formula:

CN R'-CO-Ofi wherein R represents alkyl with up to 5 carbon atoms;

alkoxy with up to 5 carbon atoms;

aryl or aralkyl;

R represents aryl or a heterocyclic group of the class consisting of furyl, pyridyl or thienyl; which transferable compound is transferable at temperature of between and 200 C. to an image-reeciving layer;

a sensitizer dye from the class of the neutrostyryl dyes,

the merocyanines or a cyanine dye containing a halogen substituted benzine ring or a heterocyclic ring derived from selenazol and the neutrostyryl dyes, the merocyanines or a cyanine dye containing a halogen substituted benzine ring or a heterocyclic ring derived from selenazol; 

